A celebration ended in sadness Saturday night in St. Clair Township, when recent high school graduate Savannah Blewett and her older brother died in a large bonfire explosion.

St. Clair County Sheriff Tim Donnellon said in a release that 27-year-old Christopher Blewett poured a large amount of gasoline on a two-story pile of wood in his backyard and, according to witnesses, invited his sister to light it on fire.

When she did, the gasoline exploded, scattering wood up to 100 yards and blowing out windows in the back of the house, located on the 6500 block of Gratiot Road.

The siblings were killed in the explosion, and three others were treated for undisclosed injuries at local hospitals.

A neighbor called authorities shortly after 9:30 p.m., prompting responses from sheriff's deputies, local police officers and at least three local fire departments.

Donnellon said alcohol was served at the party, but there was no indication that minors were drinking.

A man staying in a campground nearby told television station WXYZ that the explosion shook his RV and described the sound as a "sonic boom."

The Blewett family chose not to speak about their loss on camera, but well-wishers have been offering condolences on a Facebook page set up to remember Savannah and Christopher.

"You lost your lives in an accident that should never have happened," reads a message on the page. "We will all love and miss you dearly."

The weekend bonfire explosion occurred just weeks after a similar incident in West Michigan, where seven teenagers were injured after dousing a large brush pile with gasoline and setting it on fire.